Question

I’m trying to accumulate some values if they match a condition.
Why is this snippet returning nil, when I would expect it to return 2?

[[1, 2], [2, 3], [3, 8], [4, 2]].inject(0) { |s, e| s + e[1] if e[0] <= 1}

Isn’t inject the right method for this?

Answer 1

You should return s;

[[1, 2], [2, 3], [3, 8], [4, 2]].inject(0) { |s, e| s += e[1] if e[0] <= 1; s}

Little cleaner

[[1, 2], [2, 3], [3, 8], [4, 2]].inject(0){|s,(k,v)| s += (k<2 ? v : 0)}